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Buttons

Use Bootstrap’s custom button styles for actions in forms, dialogs, and more with support for multiple sizes, states, and more.

示例

Bootstrap 内置了几种预定义的按钮样式,每种样式都有自己的语义目的,并添加了一些额外的按钮includes several predefined button styles, each serving its own semantic purpose, with a few extras thrown in for more control.

<button type="button" class="btn btn-primary">Primary</button>
<button type="button" class="btn btn-secondary">Secondary</button>
<button type="button" class="btn btn-success">Success</button>
<button type="button" class="btn btn-danger">Danger</button>
<button type="button" class="btn btn-warning">Warning</button>
<button type="button" class="btn btn-info">Info</button>
<button type="button" class="btn btn-light">Light</button>
<button type="button" class="btn btn-dark">Dark</button>

<button type="button" class="btn btn-link">Link</button>
Conveying meaning to assistive technologies

Using color to add meaning only provides a visual indication, which will not be conveyed to users of assistive technologies – such as screen readers. Ensure that information denoted by the color is either obvious from the content itself (e.g. the visible text), or is included through alternative means, such as additional text hidden with the .visually-hidden class.

禁止文字换行

如果你不希望按钮中的文字换行的话,可以为按钮添加 .text-nowrap 类。在 Sass 代码中,你可以设置 $btn-white-space: nowrap 来禁止所有按钮中的文本换行。

可用作按钮的 HTML 标签

.btn 系列类(class)被设计为用于 <button> 元素。不过,你也可以将这些类用于 <a><input> 元素(但是某些浏览器可能会使用略有不同的渲染方式)。

.btn 系列类(class)用于 <a> 元素并触发页面上的功能(例如折叠内容),而不是链接到新页面或当前页面中的内容部分时,应当为这些链接设置 role="button" 属性,以便将链接的目的以适当的方式传递给类似屏幕阅读器的辅助工具。

Link
<a class="btn btn-primary" href="#" role="button">Link</a>
<button class="btn btn-primary" type="submit">Button</button>
<input class="btn btn-primary" type="button" value="Input">
<input class="btn btn-primary" type="submit" value="Submit">
<input class="btn btn-primary" type="reset" value="Reset">

带轮廓线的按钮

当你需要使用按钮,但不希望按钮带有背景颜色时,请将默认的修饰符类(modifier class)替换为 .btn-outline-* 系列类(class),已去除按钮上的所有背景图片和颜色。

<button type="button" class="btn btn-outline-primary">Primary</button>
<button type="button" class="btn btn-outline-secondary">Secondary</button>
<button type="button" class="btn btn-outline-success">Success</button>
<button type="button" class="btn btn-outline-danger">Danger</button>
<button type="button" class="btn btn-outline-warning">Warning</button>
<button type="button" class="btn btn-outline-info">Info</button>
<button type="button" class="btn btn-outline-light">Light</button>
<button type="button" class="btn btn-outline-dark">Dark</button>
某些按钮的样式使用了相对较浅的前景色,因此仅应在深色背景上使用才能具有足够的对比度。

按钮的尺寸

需要更大或更小的按钮吗?使用 .btn-lg.btn-sm 类可以设置按钮的不同尺寸

<button type="button" class="btn btn-primary btn-lg">Large button</button>
<button type="button" class="btn btn-secondary btn-lg">Large button</button>
<button type="button" class="btn btn-primary btn-sm">Small button</button>
<button type="button" class="btn btn-secondary btn-sm">Small button</button>

禁用状态

通过为 <button> 元素设置 disabled 属性(此属性是布尔类型的)可以使按钮看起来处于禁用状态。处于禁用状态的按钮被设置了 pointer-events: none 属性,以防止触发鼠标悬停(hover)和活动(active)状态。

<button type="button" class="btn btn-lg btn-primary" disabled>Primary button</button>
<button type="button" class="btn btn-secondary btn-lg" disabled>Button</button>

Disabled buttons using the <a> element behave a bit different:

  • <a>s don’t support the disabled attribute, so you must add the .disabled class to make it visually appear disabled.
  • Some future-friendly styles are included to disable all pointer-events on anchor buttons.
  • Disabled buttons using <a> should include the aria-disabled="true" attribute to indicate the state of the element to assistive technologies.
  • Disabled buttons using <a> should not include the href attribute.
<a class="btn btn-primary btn-lg disabled" role="button" aria-disabled="true">Primary link</a>
<a class="btn btn-secondary btn-lg disabled" role="button" aria-disabled="true">Link</a>

To cover cases where you have to keep the href attribute on a disabled link, the .disabled class uses pointer-events: none to try to disable the link functionality of <a>s. Note that this CSS property is not yet standardized for HTML, but all modern browsers support it. In addition, even in browsers that do support pointer-events: none, keyboard navigation remains unaffected, meaning that sighted keyboard users and users of assistive technologies will still be able to activate these links. So to be safe, in addition to aria-disabled="true", also include a tabindex="-1" attribute on these links to prevent them from receiving keyboard focus, and use custom JavaScript to disable their functionality altogether.

<a href="#" class="btn btn-primary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Primary link</a>
<a href="#" class="btn btn-secondary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Link</a>

Block buttons

Create responsive stacks of full-width, “block buttons” like those in Bootstrap 4 with a mix of our display and gap utilities. By using utilities instead of button specific classes, we have much greater control over spacing, alignment, and responsive behaviors.

<div class="d-grid gap-2">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

Here we create a responsive variation, starting with vertically stacked buttons until the md breakpoint, where .d-md-block replaces the .d-grid class, thus nullifying the gap-2 utility. Resize your browser to see them change.

<div class="d-grid gap-2 d-md-block">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

You can adjust the width of your block buttons with grid column width classes. For example, for a half-width “block button”, use .col-6. Center it horizontally with .mx-auto, too.

<div class="d-grid gap-2 col-6 mx-auto">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

Additional utilities can be used to adjust the alignment of buttons when horizontal. Here we’ve taken our previous responsive example and added some flex utilities and a margin utility on the button to right align the buttons when they’re no longer stacked.

<div class="d-grid gap-2 d-md-flex justify-content-md-end">
  <button class="btn btn-primary me-md-2" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

Button plugin

The button plugin allows you to create simple on/off toggle buttons.

Visually, these toggle buttons are identical to the checkbox toggle buttons. However, they are conveyed differently by assistive technologies: the checkbox toggles will be announced by screen readers as “checked”/“not checked” (since, despite their appearance, they are fundamentally still checkboxes), whereas these toggle buttons will be announced as “button”/“button pressed”. The choice between these two approaches will depend on the type of toggle you are creating, and whether or not the toggle will make sense to users when announced as a checkbox or as an actual button.

Toggle states

Add data-bs-toggle="button" to toggle a button’s active state. If you’re pre-toggling a button, you must manually add the .active class and aria-pressed="true" to ensure that it is conveyed appropriately to assistive technologies.

<button type="button" class="btn btn-primary" data-bs-toggle="button" autocomplete="off">Toggle button</button>
<button type="button" class="btn btn-primary active" data-bs-toggle="button" autocomplete="off" aria-pressed="true">Active toggle button</button>
<button type="button" class="btn btn-primary" disabled data-bs-toggle="button" autocomplete="off">Disabled toggle button</button>
<a href="#" class="btn btn-primary" role="button" data-bs-toggle="button">Toggle link</a>
<a href="#" class="btn btn-primary active" role="button" data-bs-toggle="button" aria-pressed="true">Active toggle link</a>
<a class="btn btn-primary disabled" aria-disabled="true" role="button" data-bs-toggle="button">Disabled toggle link</a>

方法

你可以使用按钮插件的构造函数来创建按钮实例,例如:

var button = document.getElementById('myButton')
var bsButton = new bootstrap.Button(button)
Method Description
toggle Toggles push state. Gives the button the appearance that it has been activated.
dispose Destroys an element's button. (Removes stored data on the DOM element)
getInstance Static method which allows you to get the button instance associated to a DOM element, you can use it like this: bootstrap.Button.getInstance(element)
getOrCreateInstance Static method which returns a button instance associated to a DOM element or create a new one in case it wasn't initialized. You can use it like this: bootstrap.Button.getOrCreateInstance(element)

For example, to toggle all buttons

var buttons = document.querySelectorAll('.btn')
buttons.forEach(function (button) {
  var button = new bootstrap.Button(button)
  button.toggle()
})

Sass

Variables

$btn-padding-y:               $input-btn-padding-y;
$btn-padding-x:               $input-btn-padding-x;
$btn-font-family:             $input-btn-font-family;
$btn-font-size:               $input-btn-font-size;
$btn-line-height:             $input-btn-line-height;
$btn-white-space:             null; // Set to `nowrap` to prevent text wrapping

$btn-padding-y-sm:            $input-btn-padding-y-sm;
$btn-padding-x-sm:            $input-btn-padding-x-sm;
$btn-font-size-sm:            $input-btn-font-size-sm;

$btn-padding-y-lg:            $input-btn-padding-y-lg;
$btn-padding-x-lg:            $input-btn-padding-x-lg;
$btn-font-size-lg:            $input-btn-font-size-lg;

$btn-border-width:            $input-btn-border-width;

$btn-font-weight:             $font-weight-normal;
$btn-box-shadow:              inset 0 1px 0 rgba($white, .15), 0 1px 1px rgba($black, .075);
$btn-focus-width:             $input-btn-focus-width;
$btn-focus-box-shadow:        $input-btn-focus-box-shadow;
$btn-disabled-opacity:        .65;
$btn-active-box-shadow:       inset 0 3px 5px rgba($black, .125);

$btn-link-color:              $link-color;
$btn-link-hover-color:        $link-hover-color;
$btn-link-disabled-color:     $gray-600;

// Allows for customizing button radius independently from global border radius
$btn-border-radius:           $border-radius;
$btn-border-radius-sm:        $border-radius-sm;
$btn-border-radius-lg:        $border-radius-lg;

$btn-transition:              color .15s ease-in-out, background-color .15s ease-in-out, border-color .15s ease-in-out, box-shadow .15s ease-in-out;

$btn-hover-bg-shade-amount:       15%;
$btn-hover-bg-tint-amount:        15%;
$btn-hover-border-shade-amount:   20%;
$btn-hover-border-tint-amount:    10%;
$btn-active-bg-shade-amount:      20%;
$btn-active-bg-tint-amount:       20%;
$btn-active-border-shade-amount:  25%;
$btn-active-border-tint-amount:   10%;

Mixins

There are three mixins for buttons: button and button outline variant mixins (both based on $theme-colors), plus a button size mixin.

@mixin button-variant(
  $background,
  $border,
  $color: color-contrast($background),
  $hover-background: if($color == $color-contrast-light, shade-color($background, $btn-hover-bg-shade-amount), tint-color($background, $btn-hover-bg-tint-amount)),
  $hover-border: if($color == $color-contrast-light, shade-color($border, $btn-hover-border-shade-amount), tint-color($border, $btn-hover-border-tint-amount)),
  $hover-color: color-contrast($hover-background),
  $active-background: if($color == $color-contrast-light, shade-color($background, $btn-active-bg-shade-amount), tint-color($background, $btn-active-bg-tint-amount)),
  $active-border: if($color == $color-contrast-light, shade-color($border, $btn-active-border-shade-amount), tint-color($border, $btn-active-border-tint-amount)),
  $active-color: color-contrast($active-background),
  $disabled-background: $background,
  $disabled-border: $border,
  $disabled-color: color-contrast($disabled-background)
) {
  color: $color;
  @include gradient-bg($background);
  border-color: $border;
  @include box-shadow($btn-box-shadow);

  &:hover {
    color: $hover-color;
    @include gradient-bg($hover-background);
    border-color: $hover-border;
  }

  .btn-check:focus + &,
  &:focus {
    color: $hover-color;
    @include gradient-bg($hover-background);
    border-color: $hover-border;
    @if $enable-shadows {
      @include box-shadow($btn-box-shadow, 0 0 0 $btn-focus-width rgba(mix($color, $border, 15%), .5));
    } @else {
      // Avoid using mixin so we can pass custom focus shadow properly
      box-shadow: 0 0 0 $btn-focus-width rgba(mix($color, $border, 15%), .5);
    }
  }

  .btn-check:checked + &,
  .btn-check:active + &,
  &:active,
  &.active,
  .show > &.dropdown-toggle {
    color: $active-color;
    background-color: $active-background;
    // Remove CSS gradients if they're enabled
    background-image: if($enable-gradients, none, null);
    border-color: $active-border;

    &:focus {
      @if $enable-shadows {
        @include box-shadow($btn-active-box-shadow, 0 0 0 $btn-focus-width rgba(mix($color, $border, 15%), .5));
      } @else {
        // Avoid using mixin so we can pass custom focus shadow properly
        box-shadow: 0 0 0 $btn-focus-width rgba(mix($color, $border, 15%), .5);
      }
    }
  }

  &:disabled,
  &.disabled {
    color: $disabled-color;
    background-color: $disabled-background;
    // Remove CSS gradients if they're enabled
    background-image: if($enable-gradients, none, null);
    border-color: $disabled-border;
  }
}
@mixin button-outline-variant(
  $color,
  $color-hover: color-contrast($color),
  $active-background: $color,
  $active-border: $color,
  $active-color: color-contrast($active-background)
) {
  color: $color;
  border-color: $color;

  &:hover {
    color: $color-hover;
    background-color: $active-background;
    border-color: $active-border;
  }

  .btn-check:focus + &,
  &:focus {
    box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
  }

  .btn-check:checked + &,
  .btn-check:active + &,
  &:active,
  &.active,
  &.dropdown-toggle.show {
    color: $active-color;
    background-color: $active-background;
    border-color: $active-border;

    &:focus {
      @if $enable-shadows {
        @include box-shadow($btn-active-box-shadow, 0 0 0 $btn-focus-width rgba($color, .5));
      } @else {
        // Avoid using mixin so we can pass custom focus shadow properly
        box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
      }
    }
  }

  &:disabled,
  &.disabled {
    color: $color;
    background-color: transparent;
  }
}
@mixin button-size($padding-y, $padding-x, $font-size, $border-radius) {
  padding: $padding-y $padding-x;
  @include font-size($font-size);
  // Manually declare to provide an override to the browser default
  @include border-radius($border-radius, 0);
}

Loops

Button variants (for regular and outline buttons) use their respective mixins with our $theme-colors map to generate the modifier classes in scss/_buttons.scss.

@each $color, $value in $theme-colors {
  .btn-#{$color} {
    @include button-variant($value, $value);
  }
}

@each $color, $value in $theme-colors {
  .btn-outline-#{$color} {
    @include button-outline-variant($value);
  }
}